Bright broad-band afterglows of gravitational wave bursts from mergers of binary neutron stars
Xuefeng Wu Purple Mountain Observatory
Chinese Center for Antarctic Astronomy Chinese Academy of Sciences
May 8, 2013
Collaborators: He Gao, Xuan Ding, Bing Zhang & Zi-Gao Dai
2013 Multi-Messenger Transient Astrophysics Workshop
KIAA, Beijing, China; May 6 - 10, 2013
How WUniverse Expands (I)
2001.9, Nanjing University
Xue-Feng
Wu
Yong-Feng
Huang
Xiang-Yu
Wang
Yi-Zhong
Fan
Bi-Ping
Gong
Zi-Gao
Dai
Tan
Lu
Da-Ming
Wei
Pawan
Kumar
Zhuo
Li
How WUniverse Expands (II)
2009.6, Penn State University
Xue-Feng
Wu
Kenji
Toma
Peter
Meszaros Alessandra
Corsi
Derek
Fox Nino
Cucchiara
How WUniverse Expands (III)
Xue-Feng
Wu
Bing
Zhang
Bin-Bin
Zhang Wei-Hua
Lei
Bo
Zhang
Wei
Deng
He
Gao Qiang
Yuan
2010.1.2, Las Vegas
~ 300 ( 0.1)Mpc z
Credit on David Shoemaker
Motivation
Adv VIRGO & LIGO
2015? 2020?
NS+NS
10.2 ~ 2000 yrEvent Rate
Zhang 2013 ApJL
http://physics.aps.org/articles/v3/29
NS-NS coalescence
Gravitational
Wave
Electromagnetic (EM) emission signal accompany with
a GWB is essential for GW identification.
http://physics.aps.org/articles/v3/29
NS-NS coalescence
Gravitational
Wave
Electromagnetic (EM) emission signal accompany with
a GWB is essential for GW identification.
The brand new channel of GW signals combining with
old channel of EM emission would lead us better
understand our universe.
http://physics.aps.org/articles/v3/29
NS-NS coalescence
Electromagnetic (EM) emission signal accompany with
a GWB is essential for GW identification.
The brand new channel of GW signals combining with
old channel of EM emission would lead us better
understand our universe.
Remnant?
http://physics.aps.org/articles/v3/29
NS-NS coalescence
Electromagnetic (EM) emission signal accompany with
a GWB is essential for GW identification.
The brand new channel of GW signals combining with
old channel of EM emission would lead us better
understand our universe.
Remnant? EOS
http://physics.aps.org/articles/v3/29
NS-NS coalescence
Electromagnetic (EM) emission signal accompany with
a GWB is essential for GW identification.
The brand new channel of GW signals combining with
old channel of EM emission would lead us better
understand our universe.
Remnant? EOS
BH
http://physics.aps.org/articles/v3/29
NS-NS coalescence
Electromagnetic (EM) emission signal accompany with
a GWB is essential for GW identification.
The brand new channel of GW signals combining with
old channel of EM emission would lead us better
understand our universe.
Remnant? EOS
BH
NS
Metzger & Berger, 2012
SGRB
Multi-band transient ~hours, days, weeks,
or even years
Li-Paczyński Nova
Opical flare ~ 1 day
Ejecta-ISM shock
Radio ~years
Li & Paczyński, 1998
Nakar& Piran, 2011
EM signals
for a BH post-merger product
Short GRBs
γ-ray Light curve
Short GRBs
X-ray afterglow plateaus: hints of magnetar?
Rowlinson et al. (2010) Rowlinson et al. (2013)
Li-Paczynski Nova / Kilonova
Metzger et al. (2010)
Radio Afterglows
Rosswog, Piran & Nakar (2012)
What if the central product is
magnetar rather than a black hole?
Why Magnetar ?
Theoretical reason Stiff EoS
Why Magnetar ?
Theoretical reason Stiff EoS
Lattimer (2012)
Stiff equation-of-state: maximum NS mass close to 2.5 M
Why Magnetar ?
Theoretical reason Stiff EoS
Observational reason
Zhang, 2013 (Ref therein)
Lattimer & Prakash (2010)
NS with mass > 2 Msun has been discovered
(e.g., PSR J0348+0432, M=2.01+/-0.04 Msun)
NS-NS systems: total mass can be ~ 2.6 Msun
Why Magnetar ?
Theoretical reason Stiff EoS
Observational reason
Zhang, 2013 (Ref therein) Based on the observations
of the SGRB X-ray afterglows.
Rowlinson et al. 2013 Rowlinson et al. 2010
GRB 090515
NS with mass > 2 Msun has been discovered
(e.g., PSR J0348+0432, M=2.01+/-0.04 Msun)
NS-NS systems: total mass can be ~ 2.6 Msun
Why Magnetar ?
Theoretical reason Stiff EoS
Observational reason
Zhang, 2013 (Ref therein) Based on the observations
of the SGRB X-ray afterglows.
Rowlinson et al. 2013 Rowlinson et al. 2010
GRB 090515
A postmerger magnetar would
be initially rotating near the
Keplerian velocity
P~1ms.
52 2
45 0, 32 10rotE erg I P
49 1 2 6 4
,0 ,15 6 0, 310sd pL erg s B R P
3 2 6 2
45 ,15 6 0, 3
0,
~ 10rot
sd p
sd
ET s I B R P
L
NS with mass > 2 Msun has been discovered
(e.g., PSR J0348+0432, M=2.01+/-0.04 Msun)
NS-NS systems: total mass can be ~ 2.6 Msun
Hotokezaka,et al., arXiv:1212.0905
Mass Ejection during NS-NS Merger
Initial velocity: 0.1 – 0.3 c
Ejected mass: 0.0001 – 0.01 Msun
Jet-ISM shock (Afterglow)
Shocked ISM
Ejecta
SGRB
Radio
Optical
X-ray
X-ray
X-
ray
Poynting
flux
MNS
Magnetar as the central product
SGRB
Late central engine activity ~Plateau & X-ray flare
Magnetic Dissipation
X-ray Afterglow
1000 ~10000 s
8 1 210 ergs cm
Ejecta-ISM shock with
Energy Injection (EI)
Multi-band transient ~hours, days, weeks,
or even years
Gao, Ding, Wu, Zhang & Dai, 2013
Zhang, 2013
Jet-ISM shock (Afterglow)
Shocked ISM
Ejecta
SGRB
Radio
Optical
X-ray
X-ray
X-
ray
Poynting
flux
MNS
Magnetar as the central product
SGRB
Late central engine activity ~Plateau & X-ray flare
Magnetic Dissipation
X-ray Afterglow
1000 ~10000 s
8 1 210 ergs cm
Ejecta-ISM shock with
Energy Injection (EI)
Multi-band transient ~hours, days, weeks,
or even years
Zhang, 2013
Gao, Ding, Wu, Zhang & Dai, 2013
Jet-ISM shock (Afterglow)
Shocked ISM
Ejecta
SGRB
Radio
Optical
X-ray
X-ray
X-
ray
Poynting
flux
MNS
Magnetar as the central product
SGRB
Late central engine activity ~Plateau & X-ray flare
Magnetic Dissipation
X-ray Afterglow
1000 ~10000 s
8 1 210 ergs cm
Ejecta-ISM shock with
Energy Injection (EI)
Multi-band transient ~hours, days, weeks,
or even years
Gao et al, 2013
Zhang, 2013
Rowlinson et al. 2013
Jet-ISM shock (Afterglow)
Shocked ISM
Ejecta
SGRB
Radio
Optical
X-ray
X-ray
X-
ray
Poynting
flux
MNS
Magnetar as the central product
SGRB
Late central engine activity ~Plateau & X-ray flare
Magnetic Dissipation
X-ray Afterglow
1000 ~10000 s
8 1 210 ergs cm
Ejecta-ISM shock with
Energy Injection (EI)
Multi-band transient ~hours, days, weeks,
or even years
Gao et al, 2013
Zhang, 2013
Magnetic Dissipation X-ray Afterglow
Flu
x (
erg
cm
-2s
-1)
t sdT
8 2 110 erg cm s
Zhang, B., 2013, ApJL, 763,22
1/3F With , one can
roughly estimate that the
optical flux could be as
bright as 17th magnitude
in R band.
The proto-magnetar would eject a
wide-beam wind, whose dissipation
would power an X-ray afterglow as
bright as~ (10−8–10−7) erg cm−2 s−1.
The duration is typically 103–104s.
Jet-ISM shock (Afterglow)
Shocked ISM
Ejecta
SGRB
Radio
Optical
X-ray
X-ray
X-
ray
Poynting
flux
MNS
Magnetar as the central product
SGRB
Late central engine activity ~Plateau & X-ray flare
Magnetic Dissipation
X-ray Afterglow
1000 ~10000 s
8 1 210 ergs cm
Ejecta-ISM shock with
Energy Injection (EI)
Multi-band transient ~hours, days, weeks,
or even years
Zhang, 2013
Gao, Ding, Wu, Zhang & Dai, 2013
ISM (n) 0L
Energy conservation equation
49 2 6 4
0 ,15 6 0, 310 pL B R P
34
3sw pM nm R
Ejecta-ISM shock with Energy Injection Gao, Ding, Wu, Zhang & Dai, 2013, arXiv:1301.0439
0
2 2 2: ( 1) ( 1)
rot
sd
dec ej sw
ET
L
T M c M c when
Dynamics depends on and , namely
and
0L ejM
pBejM
Ejecta-ISM shock with Energy Injection
For given different
leads to different
Dynamic cases.
Some of them could
be even relativistic
pB
ejM
, ,2ej ej crM M
3 2
, ,2 45 0, 3~ 6 10ej crM M I P
Non-relativistic
If
14 4~10 , ~10ejB G M M
sd decT T
Ejecta-ISM shock with Energy Injection
X-ray:
Opt:
Radio:
11 2 1~10peakF erg cm s
~10peakF mJy
7~10peakT s
~ 1peakF Jy
4~ ~10peak sdT T s
4~ ~10peak sdT T s
15 4~10 , ~10ejB G M M
~sd decT T
Ejecta-ISM shock with Energy Injection
X-ray:
Opt:
Radio:
3~ ~10peak sdT T s
9 2 1~10peakF erg cm s
~100peakF mJy
7~10peakT s
~100peakF mJy
3~ ~10peak sdT T s
15 3~10 , ~10ejB G M M
sd decT T
Ejecta-ISM shock with Energy Injection
X-ray:
Opt:
Radio:
3~ ~10peak sdT T s
10 2 1~10peakF erg cm s
~10peakF mJy
7~10peakT s
~ 1peakF Jy
3~ ~10peak sdT T s
SGRB
Flu
x (
erg
cm
-2s
-1)
t sdT
8 2 110 erg cm s
X-ray Emission in All Directions
Magnetic dissipation
sdT
Magnetic dissipation +
Ejecta-ISM shock w/ EI
SGRB
Flu
x (
erg
cm
-2s
-1)
t sdT
8 2 110 erg cm s
X-ray Emission in All Directions
Magnetic dissipation
Magnetic dissipation +
Ejecta-ISM shock w/ EI
sdT
3 410 ~10obsT s
Late Re-brightening in SGRB 080503
Late Re-brightening in SGRB 080503
--- Li-Paczynski Model
Perley et al. 2009, ApJ, 696, 1871
Late Re-brightening in SGRB 080503
--- Refreshing Shock Model
Hascoet et al. 2012, A&A, 541, A88
Ek,0 = 7 e 50 erg
Ek,inj = 30 Ek,0
ε_e = (ε_B )^0.5
ε_B = 5 e −2,
p = 2.5
n = 1 e -3 cm−3
z = 0.5
Late Re-brightening in SGRB 080503
--- Gao, Ding, Wu, Zhang & Dai (2013) Model
Ding, Gao, Wu, Zhang & Dai 2013,
in preparation
Relativistic PTF Transient PTF11agg
--- Another GWB magnetar candidate?
Cenko et al. (2013)
Event Rate by VLA Bright Radio Transient Survery
Bower & Sauer. 2011, ApJL, 728, 14
• Field of 3C 286
• 23-year archival observation
• 1.4 GHz
event rate (>350 mJy ) is
< 6×10−4 degree−2 yr−1,
or < 20 yr −1
Bright GWB afterglow rate
uncertainties:
(1) NS-NS merger
(2) Fraction of forming a massive
millisecond magnetar
How to differentiate BH and Magnetar
Gravitational Wave Signal EM Counterpart
Chirp + Ring down
BH:
Magnetar:
After the standard chirp signal and merger
phase, there should be an extended GW
emission episode afterward due to a
secular bar-mode instability of the newly
formed proto-magnetar.
BH:
SGRB: No X-ray Plateau
No-SGRB:
No X-ray
Li-Paczyński Nova
Weak Radio Signal
SGRB: w/ X-ray Plateau
No-SGRB:
X-ray detection
Bright Opt Signal
Strong Radio Signal
Magnetar:
No extended GW
emission after merger
How to differentiate BH and Magnetar
Gravitational Wave Signal EM Counterpart
Chirp + Ring down
BH:
Magnetar:
After the standard chirp signal and merger
phase, there should be an extended GW
emission episode afterward due to a
secular bar-mode instability of the newly
formed proto-magnetar.
BH:
SGRB: No X-ray Plateau
No-SGRB:
No X-ray
Li-Paczyński Nova
Weak Radio Signal
SGRB: w/ X-ray Plateau
No-SGRB:
X-ray detection
Bright Opt Signal
Strong Radio Signal
Magnetar:
No extended GW
emission after merger
Localization Error Box
Strategy to Detect EM Counterpart of GWB
~Tens of square degree
~Tens of seconds before merger
trigger Adv-LIGO
Localization Error Box
Strategy to Detect EM Counterpart of GWB
~Tens of square degree
Two kinds of strategy
1) Small field of view, with both
fast-slewing speed and high
sensitivity.
103–104s could go through
the whole Error Box
~Tens of seconds before merger
trigger Adv-LIGO
GW Localization Error Box
Strategy to Detect EM Counterpart of GWB
~Tens of square degree
Two kinds of strategy
1) Small field of view, with both
fast-slewing speed and high
sensitivity.
If 103–104s could go through
the whole Error Box
~Tens of seconds before merger
trigger Adv-LIGO
~ sd
dec
err
slew TP
A
~ 1decP
Telescope field of view
Strategy to Detect EM Counterpart of GWB
~Tens of square degree
Two kinds of strategy
2) Large field of view, with
fast-slewing capability and
moderate sensitivity.
GWAC
Einstein Probe
~Tens of seconds before merger
trigger Adv-LIGO
GW Localization Error Box
Telescope field of view
~ sd
dec
sky
slew TP
A
If 103–104s could go through
the whole sky ~ 1decP
Thank You